Showing papers by "Malcolm L. Spaulding published in 1993"

Flushing Times for the Providence River Based on Tracer Experiments

Abstract: The flushing time of the Providence River was estimated using three different data sets and three different methodologies Dye concentrations were measured following instantaneous dye releases during wet weather experiments performed by the Narragansett Bay Project between October 1988 and June 1989 These data were analyzed to obtain flushing time estimates Salinity measurements collected during the Sinbadd (Sampling In Narragansett Bay All During the Day) cruises, Spray (Sampling the Providence River All Year) cruises and wet weather experiments were used with the fraction of fresh water method and box model to calculate flushing time The Sinbadd cruises performed 4 seasonal surveys at 22 stations in Narragansett Bay during 1986 to obtain a view of the whole Narragansett Bay with respect to the concentrations of nutrients and trace metals The Spray cruises collected data in the Providence River at 10 stations to determine the relationship of nutrients and trace metals concentrations in the Seekonk and Providence rivers as a function of point source inputs Based on the flushing time estimates, an exponential relationship between freshwater inflow and flushing time was developed (correlation coefficient of 0826) The flushing time ranged from 08 d at high (90 m3 m−1) freshwater inflows to 44 d at low (20 m3 s−1) freshwater inflows The average flushing time of the Providence River was estimated as 25 d for the mean freshwater inflow of 423 m3 s−1

Influence of vibration amplitude on laminar flow over a plate vibrating at low strouhal number

Abstract: The spectral and hydrodynamic response of laminar flow over a flat plate with a vibrating section forces in sinusoidal motion with a dimensionless amplitude ratio, Ho (vibration amplitude divided by plate length) varying in the range 0.0 < Ho < 0.1 is analyzed using numerical simulations. The Reynolds number, Re, based on the length of the vibrating plate, is fixed at 1000. The flow is simulated for Strouhal number, St, = 0.25 (low frequency). The spectral characteristics are obtained by performing Fast Fourier Transform (FFT) on the pressure coefficient time series data. The hydrodynamic analysis is performed by plotting stream function contour plot in the vicinity of the vibrating section for one vibration cycle. The model predicted results show that the friction and pressure coefficients over the vibrating body vary with vibration amplitude. For low amplitude ratios, the interaction of the external flow with the vibrating section is linear and there is little up or down- stream influence. For high Ho there is considerable downstream influence of the disturbance. Nonlinear energy transfer, as evidenced by the existence of a significant first harmonic in the pressure wave, takes place between the vibrating plate and the flow field. Energy transfer to the higher harmonics is less significant.